You're right about Delance, but wrong about the rest.
Not at all races sing about lynching other races. They simply don't. And if they did, it would have less resonance because their grandparents (figuratively, if not literally, speaking) didn't actually lynch (figuratively, if not literally speaking) our grandparents (I don't know your racial heritage, WT; the above presumes that, like me, you are primarily Caucasian).
What's wrong with America these days is not overreaction to racism, but that racism is still as pervasive as it is. Great progress has been made, and thank God for that, but many want to pretend that we're basically at square one now, that racism is now a thing of the past except for a few bad apples.
I wish it were so, but it's not. Not by a long shot. Pretending that everything is ok now, that recent (and not-so-recent) history doesn't matter any more, accomplishes nothing.
I'm very proud of President Boren for his swift and righteously angry response, and of OU students and faculty of every race and color who have spoken out with passion against these bigots.